Without limiting the scope of the invention, its background is described in connection with ram air filters.
One such system is taught in U.S. Pat. No. 8,721,756, issued to Handley, et al., and is entitled “Filter construction for use with air in-take for gas turbine and methods”. Briefly, these inventors teach a cartridge filter comprising a structure that can maintain a filter medium in an air stream to filter particulates to protect a gas turbine power system and that the filter combines a mechanically adequate filter structure and an effective filter medium to obtain a useful system.
Another such system is taught in U.S. Pat. No. 8,998,130, issued to Dailey, et al., and is entitled “Self-aligning inlet plenum system for rotorcraft”. Briefly, these inventors teach an inlet system for a rotorcraft includes a cowl door assembly and a plenum assembly. The cowl door assembly includes a door member, a cowl inlet opening, and a cowl inlet duct. The plenum assembly is configured to free float in relation to the cowl door. The plenum assembly includes a plenum duct with a plenum band configured to attach the plenum assembly to an inlet opening. An aft seal is located between the aft plenum flange and a firewall, the aft seal being configured to provide a compressive contact between the plenum assembly and the firewall.
Another such system is taught in U.S. Pat. No. 3,950,157, issued to Matney, and is entitled “Ram air filter for light aircraft”. Briefly, this inventor is said to teach a ram air filter for light aircraft comprising a parallelepiped housing and a replaceable filter element. The housing comprises a base element and a cover element that are injection molded of high impact plastic and are connected together in a snap-lock manner.